She and Oscar-winning short film director (the films are short, FYI, not the man) Ari Sandel were drinking more than just sake at Nobu in El Lay, they were totally swapping spit!

Ooh!!!

So heeeeee's the reason why our perfectly proportioned lady-patriot is keeping her booty so fresh and fruity, LOL!!!

Poor, poor Ryan Seacrest!! Between his ex finding a new man and his recent Monaco misfire, the AI stud seems to be crapping out all over the world! You know, except for the whole being wildly successful and lovable part!

Back to the wonderful new couple, though — what did they dine on for dessert!? Sashimi, perhaps?! LOLz!!

Zayn previewed the duet by posting a black and white pic of himself with Swifty on his Instagram -- but hey, she is bestiez with his girlfriend Gigi Hadid, so it wouldn't be unusual that they hang out... But collab?!